DNA from a female has been found on one of the bombs used in the Boston Marathon terrorist attack, but officials say they don’t know if it belongs to someone who might have aided in making the bombs.

FBI agents investigating the bombings have visited the Rhode Island home of Tamerlan Tsarnaev's in-laws and carried away several bags, and The Wall Street Journal reports that a DNA sample has been taken from Tamerlan’s wife, Katherine Russell.

But officials said that although the only two suspects currently are men, Tamerlan and his brother Dzhokhar, the presence of third-party DNA does not mean another person was involved.

The DNA could have come from a store clerk who handled the pressure cookers, model car remote controls or other items used to build the bombs. Or it could have come from a stray hair that got into the bomb.

FBI spokesman Jason Pack confirmed that agents went to the North Kingstown, R.I., home of Katherine Russell's parents Monday. Russell has been staying there since the bombings.

Pack says the FBI visited the house as part of its investigation into the bombings. Officials told the Journal that the DNA sample was collected to see if it matched what was found on the bomb remnants.

The Journal reported that Russell’s DNA sample came after days of negotiations. Her attorneys have previously said she and her family were in shock when they learned of the allegations against her husband and brother-in-law.

Former U.S. Ambassador John Bolton said the female DNA found on the bombs could have come from anywhere but cannot be overlooked.

He told Newsmax TV’s “The Steve Malzberg Show’’ the "fact that they are looking very closely at the wife of Tamerlan Tsarnaev, the elder brother who died, is significant here. And it’s very, very hard to believe that these two brothers built all of these bombs … without outside help."

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There is reason to believe that the FBI is looking at the mother, Zubeidat Tsarnaev, over conversations she had with her son as they both became radicalized, Bolton said. “The wife, obviously, is somebody they’d have to look at and, perhaps, others as well.”

There is some logic in suspecting the brothers were not experienced bomb makers and did have outside help and direction, Bolton said, “and that’s part of what the investigation law enforcement is conducting should focus on.’’

Several other associates of the Tsarnaev brothers are being sought or talked to in an effort to find whether they had help in making the bombs or in the days after the attack. Some associates might have helped dispose of evidence, investigators say, though they haven’t determined that for certain. If so, they may have been unwitting participants.

Tamerlan Tsarnaev was killed in a gun battle with police. Dzhokhar Tsarnaev has been charged with using a weapon of mass destruction and is currently in a prison hospital facility.
The Associated Press contributed to this report.

DNA from a female has been found on one of the bombs used in the Boston Marathon terrorist attack, but officials say they don t know if it belongs to someone who might have aided in making the bombs.
FBI agents investigating the bombings have visited the Rhode Island home...